5. CONCLUSIONS
To our knowledge, this is the first genome-wide study investigating both
population genomics and bacterial communities associated
with Ceratitis capitata. Our data offer an in-depth view of
medfly population structure and yields insights into the influence of
invasion pathways on the microbial diversity. It revealed genetic
structure, with one genetic cluster in South Africa (the native range of
medfly), and then two distinct genetic clusters in the introduced range:
one associated to the Brazilian individuals and the other, clustering
specimens further distance such as Spain, Greece, Guatemala, and
Australia. Furthermore, the microbiome surveys highlighted Brazil as the
most diverse set of microbiota compared with all other sampling sites.
Both approaches (genomic and microbiome) emphasize the uniqueness of
Brazil’s population, which opens the possibility for a completely
independent colonisation route from Africa to America during the
colonial period, using the transatlantic trade routes that passed
through St. Helena Island. Museum records and ABC modelling with
supervised machine learning supported this alternative colonisation
route. In any case, further research is needed to elucidate the possible
effect of microbiota in the genomic divergence at a population level and
to identify the possible role and transmission pattern of the microbiome
in the host fly.
Worldwide medfly management requires huge financial resources. The use
of genomic tools provides an opportunity to develop a framework for a
survey of medfly invasion pathways and to identify alleles that might be
crucial for population differentiation. We suggest that future studies
should use SNPs information to create quick identification methods
(e.g., genomic tagging) that will help to inform potential novel
outbreaks to the quarantine services and allow for better development
and implementation of suitable pest management strategies.